1. Field of the Invention
This invention relates to an engine control system, and in particular to a spark timing control system for an internal combustion engine.
2. Description of the Prior Art
Japanese patent publication No. 53-56429 discloses an engine control system which adjusts spark timing in accordance with pressure within a combustion chamber or cylinder. Specifically, a pressure sensor detects the cylinder pressure. The peak of cylinder pressure is derived from the detected cylinder pressure. The spark timing is controlled in accordance with the derived peak pressure so that the cylinder pressure is limited to a predetermined level at which emission of nitrogen oxides (NOx) and hydrocarbon (HC) is acceptable,
This system has no fail safe section against damage to the pressure sensor or damage to the elecrical connection to the pressure sensor. Accordingly, if such damage occurs, the spark timing is out of control.